Adjustable inductive apparatus



April 8, 1969 J. PFANZELT 3,437,969

I ADJUSTABLE INDUCTIVE APPARATUS Filed Nov. 16, 1967 Sheet or 3 Fig.1

April 8, 1969 J. PFANZELT 3,437,969

ADJUSTABLE INDUCTIVE APPARATUS Filed Nov. 16, 1967 Sheet 2 of 5 April 8, 1969 J, PFANZELT I 3,437,969

ADJUSTABLE INDUCTIVE APPARATUS Filed Nov. 16, 1967 Sheet 3 of s Fig.11

United States Patent Int. 01. min 21 /06 US. Cl. 336134 16 Claims ABSTRACT OF THE DISCLOSURE Inductive apparatus usable, for example, as an adjustable transformer, regulator, phase shifter or choke coil comprises two relatively movable core parts of which the first is a frame providing a closed magnetic path and at least two control pole pieces which partially bridge the frame, leaving a space in.which the second core part is movable to vary the magnetic coupling between the respective control pole pieces and an opposite portion of the frame. As the total magnetic coupling surface between the first and second core parts remains constant, magnetic reaction forces opposing relative movement of the core parts are avoided. Windings provided on the first core part according to the use and desired characteristics of the apparatus include winding portions on the frame and at least one of the control pole pieces.

The present invention relates to adjustable inductive apparatus usable for many purposes, for example as adjustable transformers, voltage and current regulators, transductors, phase shifters, variable inductors, choke coils, etc.

Apparatus heretofore available has had serious dis- An object of the present invention is to provide ad-- justable inductive apparatus which avoids the aforementioned disadvantages of known arrangements and, at the same time, possesses a number of desirable properties for the control of electrical output. The adjustable apparatus in accordance with the invention works wholly without contacts, provides a wide control range including null value control, is continuously controllable without steps, works without movable windings, exhibits a constant power loss independent of the control position, exhibits the smallest possible magnetic force acting on the adjustable core part and has a small movable mass. Finally, it is usable not only as a completely stepless adjustable transformer but also for many other applications where, for example, control of voltage, phase, power factor, current or impedance is desired.

In accordance with the invention these desirable characteristics are achieved by providing an adjustable inductive apparatus with two relatively movable core parts of which the first comprises a magnetically closed annular frame which is partially bridged by at least two control pole pieces extending from one side of the frame part way to the opposite side, leaving a space in which the second core part is movable to vary the magnetic coupling between the respective control pieces and the opposite side of the frame while keeping the total magnetic coupling surface between the two core parts constant. Windings are provided on only the first core part, being wound 3,437,969 Patented Apr. 8, 1969 partl on the frame and partly on at least one of the control pole pieces. At least one winding is wound around both a control piece and a portion of the frame. Means is provided for elfecting relative movement between the core parts to vary the flux paths provided by the frame and control pole pieces and thereby vary the flux cutting the respective windings and hence the voltages induced in the windings and the inductive reactance of the windmgs.

The invention will be more fully explained with reference to preferred embodiments shown by way of example in the accompanying drawings in which:

FIG. 1 is a simplified perspective representation of a basic constructive design of apparatus in accordance with the invention, control being effected by linear adjustment of the relatively movable core parts.

FIG. 2 is a schematic representation of a portion of the arrangement according to FIG. 1 to illustrate maintaining the magnetic coupling surfaces constant.

FIG. 3 is a schematic representation of an embodiment of the invention in which control is effected by rotary adjustment.

FIGS. 4 to 21 are reduced-scale schematic representations of apparatus according to FIG. 1 with different winding arrangements, the apparatus being shown in three different adjustment positions respectively.

FIG. 1 shows a first core portion K comprising a magnetically closed outer frame R which is partially magnetically bridged by two control pole pieces P1 and P2 connected with it. The frame R may be of any suitable shape, being shown by way of example as rectangular with four sides which for convenience of reference and without limitation as to shape or position of the frame are herein referred to as an upper portion R1, side portions R2 and R3 and a lower portion R4. The core portion K is of magnetically unitary construction but for convenience of assembling the windings, the upper portion R1 may be made as a separate piece which is united with the other portions of the frame after the windings are in place. The core portions are preferably of laminated construction in accordance with good transformer core design. The second core part of the apparatu is formed as a slider Sch which slides between the inner face of the upper frame part R1 and the pole faces of the control pole pieces P1 and P2 and is linearly movable in the direction of the arrows by means of a threaded spindle Sp which is rotatably supported by bearings Hu and L and is rotatable by a crank T. A scale N on the upper frame portion R1 in conjunction with an indicator F1 on a guiding element F of the slider indicates the position of the slider or the corresponding electrical value of the apparatus. Two primary windings PrL-PIZ and Pr3Pr4 on the side portions R2 and R3, respectively, of the frame R are preferably connected in parallel in such manner that they produce in the outer frame R of the first core part K two opposing magnetic fluxes 5 and A control winding Stl-StZ encircles the left side portion R2 of the frame R and at the same time the control piece P1. On the right side, the frame portion R3 is also encircled by a secondary winding Sk1Sk2 which, as will be apparent, is constantly subject to the full effect of the magnetic flux independent of the position of the apparatus.

The illustrated apparatus is especially designed as an adjustable transformer, but can be used also as a variable choke if the control winding StIfiStZ and either the secondary winding Skl-SkZ or the primary winding Pr3- Pr4 are connected in series and fed with alternating current. The different control possibilities and corresponding manner of working of the basic construction of the apparatus illustrated in FIG. 1 will be explained later with reference to FIGS. 4 to 21.

FIG. 2 serves to illustrate how the total magnetic coupling surface KF of the apparatus is kept constant in all the positions. The figure shows parts of the upper frame portion R1 and of the control poles P1 and P2, and the slider Sch of the apparatus of FIG. 1. When the slider Sch is in a central position, as indicated by the shading, there is the following relationship:

If the slider Sch is, for example, moved toward the right to the position B, the coupling surface LX11 remains constant in all cases. On the contrary, the coupling surface with the control pole P1 is decreased by the amount v b On the other side, the coupling surface on the control pole P2 increases by the like amount v b By analogy, the same is true when the slider Sch is moved to the left from the central position to the position A. The total magnetic coupling surface KF of the apparatus as a whole remains constant in all positions so that it follows that there is no unidirectional magnetic force acting on the slider.

In the rotatably controlled embodiment of the invention illustrated in FIG. 3, the first stationary core part K comprises an outer frame R which is formed as a closed magnetic frame which is partially bridged by two control poles P1 and P2 and by a further pole piece P3 so that a second core part Sch formed as a rotor is rotatable between the pole pieces in a selected range of adjustment. The frame R is shown encircled by two primary windings Pr1'-Pr2 and Pr3Pr4 which produce in the outer frame two opposed magnetic fluxes and A control winding St1'-St2 encircles a portion of the frame R and at the same time the control pole P1. The frame R is further encircled by a secondary winding Sk1-Sk2' which is constantly affected by the total magnetic flux ZI independently of the position of the second core part Sch. The different control possibilties and corresponding manner of working will be explained in more detail in reference to FIGS. 7 to 9.

FIGS. 4 to 18 show embodiments of the invention which are formed preferably as adjustable transformers, corresponding parts being designated by the same reference numerals as in FIG. 1, namely R for the frame portion of the first core part, P1 and F2 for the two control poles and Sch for an adjustable slider. Moreover, in all of these figures, the primary windings which produce the opposing magnetic fluxes (75 and are identified by the terminals 1-2 and 3-4, the control windings by the terminals 5-6 or 5-6, the secondary windings by the terminals 7-8 and the auxiliary windings by H1 and H2. While the core parts have been shown in the shape of those of FIG. 1, it will be understood that the winding arrangements illustrated in FIGS. 14 to 18 and also in FIGS. 19 to 21 are also applicable to other core shapes, such as those shown in FIG. 3.

FIGS. 4 to 6 show a simple embodiment of the invention as a continuously stepless controllable adjustable transformer which is designed in the simplest manner with reference to the windings yet is advantageously usable in a variety of ways. Starting with the position of the apparatus shown in FIG. 4, with alternating current fed to both primary windings, no voltage is induced in the control winding 5-6 because the flux flows in a closed path inside the control winding 5-6 and flux 4: is idle. If the slider Sch is in the position shown in FIG. 5, the flux is, as before, closed inside the control winding 5-6 so that it does not induce any voltage in the control winding but the flux is operatively interlinked with the control winding 5-6 and induces in the control winding a voltage according to the winding relation between the primary winding 3-4 and the control winding 5-6. In the position of FIG. 6, the magnetic fluxes are so directed that the flux 5 is operatively interlinked with the control winding 56 and induces in it a voltage according to the transformer ratio of the winding while the flux is idle. It is thus apparent that in all adjustment positions of the apparatus between those of FIGS. 4 and 5 and between those of FIGS. 4 and 6 the intermediate voltage values are continuously adjustable and that, starting from the position of FIG. 4, the phase of the voltage induced in the control winding 5-6 is reversed according to whether the slider Sch is moved toward the left or toward the right.

The arrangement according to FIGS. 7 to 9 differs from that of FIGS. 4 to 6 only in that there is further provided a secondary winding 7-8 which, as seen in the drawing, is traversed by the flux in all positions of the apparatus. If the secondary winding is connected in series with the control winding 56, it results that in the position shown in FIG. 7 a high voltage value will be induced in both of these windings because the flux is interlinked with the control winding 5-6 and the flux is interlinked with the secondary winding 7-8. In the position shown in FIG. 8, there is proxided an intermediate voltage value at the output because now only the flux is linked with the secondary winding 7-8, the flux being closed inside the control winding 5-6 and hence ineffective. In the position shown in FIG. 9 (with like number of turns of the control winding and the secondary winding), the voltage value at the output is zero because the flux is closed inside the control winding 5-6 and is hence ineffective while the flux 4J produces an intermediate voltage value in the secondary winding 7-8, but the same flux 4: produces in the control winding 5-6 a voltage of the same value but reversed in phase so that the two voltages cancel one another. It will be noted that the winding arrangement shown in FIGS. 7-9 corresponds to that of FIG. 3 and hence the foregoing explanation of operation also applies to the apparatus of FIG. 3.

It will be apparent from the foregoing figures that a phase reversal in the control winding 5-6 can be obtained, as described with reference to FIGS. 4 to 6 even without the described connection of the secondary winding 7-8. In this event, a constant voltage can be taken from the winding 7-8 independently of the position of the apparatus.

The arrangement according to FIGS. 10 to 12 differs from that of FIGS. 7 to 9 in that the control winding 5-6 is not wound wholly around the control pole piece P1 but a part of the winding is around only the frame R. This arrangement of the control winding is also used in the apparatus shown in FIG. 3. In this manner, the control range of the apparatus can be selected as desired by the relationship of these winding portions while maintaining the full mechanical range of movement of the slider Sch. This embodiment is particularly advantageous for use, for example, in the electric arc welding technique or for voltage stabilization where, instead of a control range between the zero and a high value, a precise control in a more or less narrow range is needed. With this arrangement, the primary and secondary windings can be magnetically coupled more closely because the winding portion of the control winding 5-6 that encircles only the frame R picks up the stray field of the primary winding 1-2. Otherwise, the operation of the apparatus corresponds to that of FIGS. 7 to 9 already described. Through a selected relationship between the number of turns of the control winding 5-6 and the secondary winding 7-8, on the one hand, and between the turns of the control winding embracing only the frame and those embracing the control pole, a phase reversal can be obtained. When the last-mentioned winding portion of the control winding 5-6 is unsymmetrical, i.e., in the positions shown in FIGS. 10 and 12, a phase reversal with variable voltage values is produced.

The arrangement according to FIGS. 13 to 16 is provided with two control windings 5-6 and 5'6. From these two windings, there can be taken two electrically separable voltages which, at the same time interval, have different phase positions. With the apparatus in the position shown in FIG. 14, the flux (p first induces in the control winding 5'-6' a voltage depending on the winding relation with a phase position x and secondly induces in the control winding 5-6 a voltage likewise dependent on the winding relationship with the phase position y. The flux 90 is closed inside the control winding 56 and is hence ineffective. In the position shown in FIG. 15, the flux (p is closed inside the control winding 5'-6' and is hence ineffective while the flux 1 first induces in the cont-r01 winding 56 a voltage with a phase position x and secondly induces in the control winding 5'-6 a voltage with the phase position y. In the position shown in FIG. 13, it will be apparent that no voltage is induced in either the control winding 5-6 nor in the control winding 5 6 because both magnetic fluxes (p and (p are closed inside the respective windings.

-In the arrangement of FIGS. 16 to 18, in addition to the two primary windings 1-2 and 3-4, a control winding 5-6 and a secondary winding 7-8, there are two auxiliary windings H1 and H2 of which one encircles the control pole P2 and the other encircles a portion of the frame R between the two control poles P1 and P2. The manner of operation is basically the same as has ben described with reference to FIGS. 7 to 9 except only that control of the windings H1 and H2 is effected by the position of the slider Sch. For example, in the position shown in FIG. 16, no voltage is induced in the auxiliary winding H1 because it is not magnetically linked with either the flux (p nor the flux p In the auxiliary winding H2, on the other hand, the flux (p induces a voltage with a value depending on the number of turns. If the slider Sch is moved to the position shown in FIG. 17, no voltage is produced in auxiliary H2 while in winding H1 a voltage with the phase position x is produced by the flux (p If the slider Sch is in the position shown in FIG. .18, the auxiliary winding H2 is linked with both of fluxes (p and c and, moreover, a voltage with the phase position y is induced in the auxiliary winding H1 by the flux ir The voltages induced in the auxiliary windings can, for example, be advantageously used for certain switching or control purposes without requiring additional power supplies.

As mentioned above, the auxiliary winding H1, starting from the position in FIG. 16, is controllable between two high voltage values with opposite phase relation. It will be apparent that the apparatus shown in FIGS. 16 to 18 is usable in the manner of a continuously controllable adjustable transformer using only the two primary windings 1-2 and 3-4 and the auxiliary winding H1.

Moreover, the apparatus can be so operated that, in addition to the already mentioned secondary winding 7 8, there is a further secondary winding associated with the primary winding 1-2 and both secondary windings are so electrically connected with the auxiliary winding H1 that the control volt-age induced in the auxiliary winding H1 can, according to the position of the apparatus, be added to or substracted from the constant voltages induced in the secondary windings.

FIGS. 19 to 21 show an embodiment of the invention as a continuously variable choke. The apparatus is provided with only two windings W1 and W2 of which one (W1) encircles the frame R and, at the same time, the control pole P1 and the other '(W2) encircles only the frame. The two windings are connected in series and when an alternating current is applied to the terminals A E, two opposing fluxes (p and (p are produced. The impedance of the apparatus is thereby variable through a w1de range, i.e. practically between compound impedance and a pure resistance. FIG. 19 shows a position of the slider Sch in which both magnetic fluxes (p and 0 have a magnetic path with minimum magnetic resistance. In this position, the self-inductance and hence the compound impedance of the apparatus is maximum. On the other hand, when the slider is in the position shown in FIG. 20, both magnetic fluxes rp and (p have only a limited cross-section of the slider through which to flow so that the self-inductance and hence the impedance is substantially limited. In the position shown in FIG. 2-1, the two fluxes (p and (p suppress one another and there remains practically only the ohmic resistance of the apparatus. In this position, the apparatus acts practically like two chokes with open air cores.

In addition to the embodiments illustrated in the drawings, other arrangements of the coils are possible within the scope of the invention. For example, additional secondary windings may be aranged on the frame to provide a constant voltage of selected value independently of the position of the apparatus so as to avoid the cost of additional transformers needed for control purposes. Moreover, the short-circuit voltage of the apparatus, i.e. the magnetic coupling between the primary and secondary, can be varied in the manner that the windings interlinked with one another can encircle the same or different portions of the frame. The invention is thus in no way limited to the preferred embodiment illustrated in the drawings. It is desirable that all embodiments, in spite of the different electrical control capabilities, have the same basic construction so that economical production is assured.

What I claim is:

1. Adjustable inductive apparatus comprising two relatively movable iron core parts of which the first core part comprises a magnetically closed frame and at least two control pole pieces connected with an partially bridging the frame with a space between the control pole pieces and an opposite portion of the frame, the second core part being received in said space and being movable to vary the magnetic coupling between the individual control pole pieces and the frame while maintaining constant the total magnetic coupling surface between the first and second core parts, at least two windings on the first core part only, said windings comprising windings arranged to produce two opposing magnetic fluxes in the frame, at least a portion of at least one winding encircling one of said control pole pieces and a portion of the frame, and means for effecting relative movement of said core parts to vary flux paths provided by said core parts and thereby vary the flux interlinked with at least one winding.

2. Apparatus according to claim 1, in which said second core part has a constant magnetic coupling surface with said frame and when in a central position, has magnetic coupling surfaces engaging approximately half of a pole face of each of said control pole pieces, the area of engagement with one control pole piece being increased, upon movement of said second core part from said central position, by an amount substantially equal to a corresponding decrease in the area of engagement with the other of said control pole pieces.

3. Apparatus according to claim 1, in which the air gaps between the core parts and the sum of the flux paths provided by the core parts are constant in all positions of the core parts relative to one another.

4. Apparatus according to claim 1, in which the second core part is rotatable about an axis relative to the first core part.

5. Apparatus according to claim 1, in which the second core part is linearly movable relative to the first core part.

6. Apparatus according to claim 5, in which a portion of the frame opposite said control pole pieces has a plane surface and said control pole pieces have plane pole faces parallel to said plane surface of the frame, said second core part comprising a slider in sliding engagement with said plane surfaces of the frame and said pole faces.

7. Apparatus according to claim 1, in which each control pole piece has at least twice the cross-sectional area of the frame.

8. Apparatus according to claim 1, in which said windings comprise two windings connected in series, one of said windings embracing the frame and one control pole piece and the other embracing only the frame.

9. Apparatus according to claim 1, in which said winding comprise two windings each embracing only the frame and arranged to produce opposing fluxes in opposite portions of the frame, and at least one control winding embracing the frame and one of said control pole pieces.

10. Apparatus according to claim 9, in which said second core part is movable relative to said first core part to a first position in which said control winding is not affected by either of said fluxes, a second position in which said control winding is interlinked with one of said fluxes only, a third position in which said control winding is interlinked with the other of said fluxes only and intermediate positions between said first and second positions and between said first and third positions.

11. Apparatus according to claim 10, in which said windings further include at least one secondary winding arranged to be interlinked with one of said fluxes in all positions of said core parts.

12. Apparatus according to claim 11, in which a primary winding and at least one secondary winding embrace the same portion of the frame.

13. Apparatus according to claim 9, in which a primary winding and at least one control winding are on the same portion of the frame.

14. Apparatus according to claim 1, in which the wind ings include a control winding having a portion embracing the frame and one of said control pole pieces and another portion embracing only the frame.

15. 'Apparatus according to claim 1, in which the windings include at leaast one auxiliary winding embracing one of said control pole pieces only.

16. Apparatus according to claim 1, in which the windings include at least one auxiliary winding embracing a portion of the frame between said control pole pieces.

References Cited UNITED STATES PATENTS 2,460,921 2/1949 Candy 336133 3,152,311 10/1964 Bojarski 336-132 3,281,655 10/1966 Blasingame 336l35 XR 3,368,142 2/1968 Bouchard et al. 336135 XR LEWIS H. MYERS, Primary Examiner.

T. J. KOZMA, Assistant Examiner.

US. Cl. X.R. 336-135 

